On Mon, Nov 14, 2016 at 09:14:57PM +0100, Sebastian Andrzej Siewior wrote:
> This also means that all feature tests fail unless the -fno-PIE is
> there.
>
> Acked-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
>
> This thing gcc v3.4 only but I intend to update the min requirement to
> alteast gcc v3.4 to cover this. As per hpa gcc v3.4 is the lowest
> version should be used for x86…
Ah yes, here's a v1.1.
Let's leave the cc-option check until we sort out the min supported
gcc version.
CC: stable too.
Thanks!
---
From: Borislav Petkov <bp@xxxxxxx>
Date: Mon, 14 Nov 2016 19:41:31 +0100
Subject: [PATCH] kbuild: Steal gcc's pie from the very beginning
So Sebastian turned off the PIE for kernel builds but that was too late
- Kbuild.include already uses KBUILD_CFLAGS and trying to disable gcc
options with, say cc-disable-warning, fails:
gcc -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs
...
-Wno-sign-compare -fno-asynchronous-unwind-tables -Wframe-address -c -x c /dev/null -o .31392.tmp
/dev/null:1:0: error: code model kernel does not support PIC mode
because that returns an error and we can't disable the warning. For
example in this case:
KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
which leads to gcc issuing all those warnings again.
So let's turn off PIE/PIC at the earliest possible moment, when we
declare KBUILD_CFLAGS so that cc-disable-warning picks it up too.
Also, we need the $(call cc-option ...) because -fno-PIE is supported
since gcc v3.4 and our lowest supported gcc version is 3.2 right now.
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
Makefile | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/Makefile b/Makefile
index 3ff1fb26d8b2..9bc877d073d7 100644
--- a/Makefile
+++ b/Makefile
@@ -399,11 +399,12 @@ KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
-fno-strict-aliasing -fno-common \
-Werror-implicit-function-declaration \
-Wno-format-security \
- -std=gnu89
+ -std=gnu89 $(call cc-option,-fno-PIE)
+
KBUILD_AFLAGS_KERNEL :=
KBUILD_CFLAGS_KERNEL :=
-KBUILD_AFLAGS := -D__ASSEMBLY__
+KBUILD_AFLAGS := -D__ASSEMBLY__ $(call cc-option,-fno-PIE)
KBUILD_AFLAGS_MODULE := -DMODULE
KBUILD_CFLAGS_MODULE := -DMODULE
KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds
@@ -621,8 +622,6 @@ include arch/$(SRCARCH)/Makefile
KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
-KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
-KBUILD_AFLAGS += $(call cc-option,-fno-PIE)
ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
KBUILD_CFLAGS += $(call cc-option,-ffunction-sections,)
--
2.10.0
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
